Pneumomediastinum following a stab wound to the chest

Description

Pneumomediastinum (PM) relates to air collection around the mediastinal structures. It is classified into spontaneous PM, without any obvious primary source, and secondary PM, with a specific responsible pathologic event, such as trauma, intrathoracic infections or violation of the aerodigestive tract.¹ The prevalence of PM in major trauma centres ranged from 1% to 5.2% of all patients with chest trauma.² PM alone does not predict severe injury, however, it warrants detailed investigation if clinical symptoms are present.²

We present a case of a 16-year-old boy who presented to our emergency department with a stab wound to the left chest, at the level of the fourth intercostal space in the midaxillary line. He was haemodynamically stable and saturating 99% on room air. As shown on chest x-ray (figure 1), a radiolucent outline around the right border of the heart indicated major intrathoracic injuries.³ We proceeded with CT scan of chest that showed bilateral pneumothoraces with PM without significant intrathoracic injuries (figure 2). He underwent conservative treatment as the mediastinum will slowly resorb air into the cavity. Breathing high-flow oxygen will increase the absorption of air.

Figure 1.

Portable AP chest x-ray with radiolucent outline around the right border of the heart.

Figure 2.

CT scan of the chest with area of pneumomediastinum (arrow).